Taxonomic revision of the Ethiopian genus Canthyporus (Coleoptera Dytiscidae)

The genus Canthyporus Zimmermann, 1919, is revised. A total of 35 species are recognized, all of them distributed within the Ethiopian Region, and with a centre of diversity in the South African Western Cape province. Descriptions of all species are given together with illustrations of habitus and male and female genitalia. A key to species (males), distribution maps, and ecological information are provided. Four new species are described from South Africa: Canthyporus aenigmaticus n.sp., C. nimius n.sp., C. turneri n.sp., and C. wewalkai n.sp. The species C. congener Omer-Cooper, 1956, is regarded as valid and not as a junior synonym of C. canthydroides (Régimbart, 1895). Lectotypes are designated for the following ten names: C. alvei Omer-Cooper, 1965, C. consuetus Omer-Cooper, 1965, C. latus Omer-Cooper, 1965, C. lowryi Omer-Cooper, 1965, C. nebulosus Omer-Cooper, 1965, C. similator Zimmermann, 1923, C. simulator Guignot, 1959, C. testaceus Zimmermann, 1923, Hydroporus collaris Boheman, 1848, and Hydroporus hottentottus Gemminger & Harold, 1868. A parsimony analysis based on 32 morphological characters found 28 shortest trees. Monophyly of the genus Canthyporus is supported mainly by the presence of an anterior ligula on the ventral side of the elytron. Four species groups are recognized within the genus: (1) canthydroides group, including ten species in Namibia and South Africa; (2) exilis group, including four species in Lesotho and South Africa; (3) hottentottus group, including 18 species from the Democratic Republic of the Congo, Ethiopia, Kenya, Lesotho, Madagascar, South Africa, Swaziland, Tanzania, and Zimbabwe; and (4) lateralis group, including three species from South Africa.